ABSTRACT
Overexpression of erbB2 is associated with resistance to apoptosis. We explored whether high level of erbB2 expression by cancer cells allows their targeting using an erbB2-binding peptide (LTVSPWY) attached to the proapoptotic alpha-tocopheryl succinate (alpha-TOS). Treating erbB2-low or erbB2-high cells with alpha-TOS induced similar levels of apoptosis, whereas alpha-TOS-LTVSPWY induced greater levels of apoptosis in erbB2-high cells. alpha-TOS rapidly accumulated in erbB2-high cells exposed to alpha-TOS-LTVSPWY. The extent of apoptosis induced in erbB2-high cells by alpha-TOS-LTVSPWY was suppressed by erbB2 RNA interference as well as by inhibition of either endocytotic or lysosomal function. alpha-TOS-LTVSPWY reduced erbB2-high breast carcinomas in FVB/N c-neu transgenic mice. We conclude that a conjugate of a peptide targeting alpha-TOS to erbB2-overexpressing cancer cells induces rapid apoptosis and efficiently suppresses erbB2-positive breast tumors.
Subject(s)
Breast Neoplasms/drug therapy , Breast Neoplasms/metabolism , Oligopeptides/pharmacokinetics , Receptor, ErbB-2/biosynthesis , Vitamin E/analogs & derivatives , Breast Neoplasms/enzymology , Cell Line, Tumor , Humans , Oligopeptides/administration & dosage , Protein Binding , Receptor, ErbB-2/metabolism , Tocopherols , Vitamin E/administration & dosage , Vitamin E/pharmacokineticsABSTRACT
Comblike glycodendrimers were prepared by the chemoselective ligation of cysteine-modified glycopeptides (1-7) with a 3-maleimidopropionate-modified linear synthetic carrier (8). Glycodendrimers bearing mono-, di-, or tri-Tn clusters (9-11) were tested as inhibitors using plant and mammalian lectins. In the former group, the Codium fragile lectin showed moderate discrimination among 9, 10, and 11. In the latter group, A and B isoforms of rat NKR-P1 lectin strongly discriminated between 9 and 10. 10 caused a 4-fold increase in killing of the NK resistant tumor cell lines at concentrations as low as 10(-8) M. Surprisingly, 11 interacted exclusively with the rat NKR-P1B isoform and inhibited efficiently natural killing in both rats and humans, even in the presence of the activating compounds 9 and 10. Dinitrophenol haptenization or influenza virus hemagglutinin T-cell epitope conjugation increased the immunogenicity of the parent compounds and resulted in the production of Tn specific antibodies.
Subject(s)
Antigens, Tumor-Associated, Carbohydrate/chemistry , Dendrimers/chemical synthesis , Killer Cells, Natural/drug effects , Lectins/chemistry , 2,4-Dinitrophenol/chemistry , Animals , Antibody Formation , Antigens, Tumor-Associated, Carbohydrate/immunology , Cysteine/chemistry , Cytotoxicity, Immunologic , Dendrimers/chemistry , Dendrimers/pharmacology , Epitopes , Female , Glycopeptides/chemistry , Haptens , Hemagglutinin Glycoproteins, Influenza Virus/chemistry , Humans , Immunoglobulin G/biosynthesis , Immunoglobulin M/biosynthesis , Jurkat Cells , Killer Cells, Natural/immunology , Mice , Mice, Inbred BALB C , Plant Lectins/chemistry , Protein Binding , Protein Isoforms/chemistry , Rats , Receptors, Immunologic/chemistry , T-Lymphocytes/immunologyABSTRACT
Four monoepitopic MAPs (MAP A, B, C and E) and one bis-diepitopic MAP B-E derived fromthe primary sequence of Schistosoma mansoni glyceraldehyde 3-phosphate dehydrogenase, previously tested in BALB/c mice, were examined for their immunogenicity and protective capacity in C57BL/6 mice. Despite multimerization into MAPs, MAP Aand MAP C were poorly immunogenic. In contrast toBALB/c mice, MAP E was non-immunogenic in C57BL/6 mice. Peptide B in the form of MAP B orbis-diepitopic MAPB-E elicited immune responses in C57BL/6 mice that were associated with a significant decrease in worm burden. The MAPs were prepared by the stepwise solid-phase peptide synthesis using Boc/Bzl chemistry, successfully purified on the RP-HPLC column and characterized by RP-HPLC, HPCE and MALDI-TOF MS techniques. A general strategy for MAPs purification is discussed here and the purification of MAP Band MAP E is documented in detail.
Subject(s)
Antigens, Helminth/chemistry , Antigens, Helminth/immunology , Glyceraldehyde-3-Phosphate Dehydrogenases/immunology , Peptides/immunology , Schistosoma mansoni/immunology , Schistosomiasis mansoni/prevention & control , Amino Acid Sequence , Animals , Antibodies, Helminth/immunology , Cytokines/immunology , Epitopes/chemistry , Epitopes/immunology , Female , Glyceraldehyde-3-Phosphate Dehydrogenases/chemistry , Mice , Mice, Inbred C57BL , Molecular Sequence Data , Peptides/chemical synthesis , Peptides/chemistry , Schistosoma mansoni/enzymologyABSTRACT
Six peptides, A, B1, B, C, D and E derived from the primary sequence of Schistosoma mansoni glyceraldehyde 3-phosphate dehydrogenase (SG3PDH) were selected based on lowest homology to human G3PDH and used for immunization of BALB/c mice. Peptides B1 and D induced immunoglobulin (Ig) G1, IgG2a and IgG2b antibodies that reacted with native and denatured SG3PDH, and were associated with significant (P<0.05) increase in fecundity and burden of challenge worms, respectively. Peptides A, B, C and E elicited a modest cellular immune response, IgG2a and/or IgG2b antibodies, and no effect on challenge worm burden. In contrast, tetrameric multiple antigen peptide (MAP) constructs A, B, C or E elicited strong cellular immune responses and production of IgG1 and/or IgG2a and IgG2b antibodies against the homologous MAP and peptide and SG3PDH. The immune responses were associated with significant (P<0.05) decrease in challenge worm burden for MAP B, and significant (P<0.05) reduction in egg count per worm couple for MAP C or E. The data together indicated the nature and effect of immune responses vary for each SG3PDH-derived peptide.
